Energy and us

What is energy?

When you google “Energy”, the first results page displays almost exclusively electricity and gas plans. Amidst these commercial offers lies one shy little Wikipedia article on a physical concept. This browsing experience reflects the most common relation that we have with energy: energy is something we trade. Energy is a commodity that we pay for just as when we buy a coffee. However, before being a commodity, energy is a physical quantity. Energy is the mark of transformation: every time something changes around you, energy comes into play. Just as mass and temperature, energy has a unit (kWh for instance) and can be measured. Some transformations are common in our everyday life:

  • Change in speed: fuel provides energy when you accelerate with your car.
  • Change in temperature: electricity provides energy when you turn on the air conditioning.
  • Change in chemical composition: when you eat food, the digestive process, which converts food into nutrients that can be absorbed by the body, consumes energy.
  • Change in height: when you climb a mountain, your body needs energy to fight against the gravitational field.
  • Change in the form of an object: when you slice veggies with a knife, you communicate energy with your arm.

Just as many physical concepts, energy obeys two fundamental laws that cannot be broken. One of them called the conservation law states a fact that is very intuitive for material objects: in a closed system, energy cannot be created nor destroyed. Therefore, the terms “generate”, “produce” or “consume” are somehow inappropriate for energy. A more accurate term would be “to convert”. Another conclusion that can be drawn from this law is that we can only use energy that already exists in the environment.

Energy consumption: a historical perspective 

Historically, our body was the only energy converter that we possessed. The energy that we get from food can be used in the form of mechanical energy with our arms and legs. However, we realised that we could leverage other forms of energy (fossil fuels) to be used by new types of converters (machines). This is the beginning of the industrial revolution. Nowadays, if you need a kWh of energy, hiring someone to do the job is uneconomic compared to fossil fuels as per the table below.

Sustainable Chart

Abundant energy has permitted to put our bodies at rest while machines work for us to produce our goods and services. This is what allows us to have the comfort that we sometimes take for granted. If machines were not working for us, we would not have all these infrastructures, transport systems, electronic devices or sanitary and health systems. All the products that you may see around you is nothing but natural resources transformed by machines. Energy is what we feed machines with when we want to transform natural resources into things that are more valuable in our view. For instance, ores are more valuable to us when used to manufacture a laptop rather than left in the ground, wood is more valuable to us when used to build a chair, or a table and limestone is more valuable to us when used to produce cement and build infrastructures.

In that respect, fossil fuels are cheap in economic terms. In physical terms, it means that they have high energy density, they are easy to access and to use.

Consequently, the average energy consumption per capita has increased more than fourfold over the last two decades as per the graph below (BP, 2018; Gapminder; Smil, 2017; United Nations). We do not always see where energy comes into play in the economy but still, our appetite to transform the environnment has never faltered, and it is still largely met by fossil fuels.

Elliot MARI

Energy Researcher at Sustainable Energy Network Solutions

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